The present invention relates to member and method for chucking a substrate and, more specifically, to a chucking member rotating with a substrate while chucking a edge portion of the substrate and a method for chucking a substrate using the chucking member.
Through a variety of processes, desired patterns are formed on a substrate such as a semiconductor substrate, a glass substrate or liquid crystal panel. In etching and cleaning processes, a wafer spins to remove residues or thin films thereon. While spinning a substrate such as a wafer at thousands of RPM, deionized water (DI water) or etching solution or cleaning solution is supplied. Undoubtedly, the substrate spinning operation has been identically applied to not only a cleaning process but also other semiconductor manufacturing processes such as a photoresist process. Various technical matters concerned with a spin head for spinning a wafer are disclosed in U.S. Pat. No. 5,860,181, to Mackawa et al.
Generally, there are two methods of holding a wafer. One is that the rear surface of a wafer is vacuum-adsorbed to hold the wafer, and the other is that the edge of a wafer is mechanically fixed by means of a support member from the edge of the wafer to hold the wafer. In the latter method, a chucking pin which is eccentric from a rotation shaft rotates to come in contact with the edge of a wafer. While being in contact with the edge of the wafer, a plurality of chucking pins support the wafer. The supported wafer rotates at a high speed and a treating chemical is supplied to a top surface of the rotating wafer.
Unfortunately, conventional chucking pins have disadvantages as follows:
First, a vortex is generated at the rear end of a chucking pin due to the shape of the chucking pin. A rotating wafer causes a vortex to be generated in a direction opposite to the rotation direction of the wafer. That is, when the wafer rotates anticlockwise, a clockwise air current is generated due to the rotation of the wafer. The air current flows outside the wafer while surrounding a circumferential surface of the chucking pin. The air current flowing along the circumferential surface of the chucking pin causes a vortex to be generated at the rear end of the chucking pin. The vortex prevents the air current to smoothly flow outside the wafer.
Second, a cleaning solution supplied to a wafer rear surface and drained to the outside along the wafer rear surface may reflow in the wafer rear surface due to a chucking pin approaching the wafer rear surface while chucking a wafer. Thus, the wafer rear surface may be contaminated.